Hyperkinetic1 and Shaker5 are neurological mutants of Drosophila melanogaster with reduced life span as compared with their wild-type background strain. The reduction in longevity has been shown to be correlated with an increased activity level and rate of O2 consumption. Studies with mosaics have shown that a possible center for aging exists within the thorax. Histochemical and biochemical concomitants of aging will be compared in the wild-type and mutant strains to determine whether correlations exist between these processes and the life spans of the individual strains. In this way specific physiological events may be established as aging landmarks. Flight mutants exist for which it is proposed to study the mutant physiological properties. The flight motor system is particularly well-suited for the study of mechanisms by which genes control neuronal organization, function and behavior. Mosaic animals may then permit the identification of the part of the animal which is relevant to the abnormal behavior. The mutant focus can then be made available for histological, electrophysiological and ultimately, biochemical analysis. It is proposed to find the cells that the Hyperkinetic and paralyticts mutants act upon the alter the motor activities of the leg. By genetic manipulations the roles of the respective cells in leg function may be revealed and at the same time an understanding of the defects caused by the mutations may be gained.